I'm rebuilding a rear (derailier) wheel as, to be frank, I used spokes
that were slightly smaller in diameter on the cassette side of the
wheel then probably wise, and had occasional spoke breakage. I finally
got some slightly larger diameter spokes and am lacing the cassette
side of the wheel.

Over probably a couple of years I had four spokes break, one at a
time, all were what Sheldon referred to as trailing spokes, the ones
that have the highest strain when pedaling, and all broke at the
middle of the bend at the head end.

While I was lacing the wheel with the new spokes I got to wondering
whether the side of the hub flange that spoke heads were on might have
had any effect on strength.

I have always laced 36 hole wheels over three for rear wheels and over
two for front wheels with the trailing spoke heads on the outside of
the hub flange and the leading spokes with the heads on the inside of
the flange, as I believe that Sheldon recommended.

But I also remember someone here with a rant about rear wheel lacing
who I think was recommending that on the cassette side that the heads
should all be toward the outside of the flange. I assumes to prevent
damaging spokes if the chain were to come off the largest cassette cog
and jam between the spokes and the cassette.

This is the only wheel I've had problems with and I deliberately
bought the bits and pieces with the idea of long life in mind -
cartridge wheel bearings and medium weight rim with eyelets, etc., and
as this is the only wheel that I've had problems with I'm fairly sure
that my wheel building technique is reasonably effective.

Any thoughts on spoke head orientation and the effect on spoke
strength.

No, but the one time I had that I had over tensioned the wheel. Exact
symptoms you described. Backed off all the spokes, never had a breakage
in the subsequent 4(?) years.

Could be. I rarely use a spoke tension gauge and just tighten things
until they feel right so I might have over tensioned that wheel.
--
Cheers,

I'm rebuilding a rear (derailier) wheel as, to be frank, I used spokes
that were slightly smaller in diameter on the cassette side of the
wheel then probably wise, and had occasional spoke breakage. I finally
got some slightly larger diameter spokes and am lacing the cassette
side of the wheel.

Over probably a couple of years I had four spokes break, one at a
time, all were what Sheldon referred to as trailing spokes, the ones
that have the highest strain when pedaling, and all broke at the
middle of the bend at the head end.

While I was lacing the wheel with the new spokes I got to wondering
whether the side of the hub flange that spoke heads were on might have
had any effect on strength.

I have always laced 36 hole wheels over three for rear wheels and over
two for front wheels with the trailing spoke heads on the outside of
the hub flange and the leading spokes with the heads on the inside of
the flange, as I believe that Sheldon recommended.

But I also remember someone here with a rant about rear wheel lacing
who I think was recommending that on the cassette side that the heads
should all be toward the outside of the flange. I assumes to prevent
damaging spokes if the chain were to come off the largest cassette cog
and jam between the spokes and the cassette.

This is the only wheel I've had problems with and I deliberately
bought the bits and pieces with the idea of long life in mind -
cartridge wheel bearings and medium weight rim with eyelets, etc., and
as this is the only wheel that I've had problems with I'm fairly sure
that my wheel building technique is reasonably effective.

Any thoughts on spoke head orientation and the effect on spoke
strength.

Well, the closest topic to the subject I can find in Jobst Brandt's book
is regarding mirror image spoking of left & right flanges, vs.
identical spoking. He says the differences are so small that the debate
is entirely academic.

I didn't always agree with Brandt, by any means, but I to believe that
he was correct here. In fact I suspect that differences are often
small enough that they are academic.

Remember when everyone was building super light aluminum wheels? And
today we are told that light weight isn't important as aerodynamic
wheels are so much better :-)

His detailed wheel building instructions have the pulling (i.e.
trailing) spoke heads on the outside, toward the cogs. That's how I've
always done mine. I almost never break spokes. BTW, I do use 36 spokes
in all my wheels, except 48 for the tandem's rear wheel.

I wonder if there's any mismatch between your troublesome hub's spoke
hole diameter and your spoke diameter? And are the hub's holes countersunk?

The wheels were originally built with new hubs, spokes, rims, etc.,
and as I remember everything fitted properly.
--
Cheers,

I'm rebuilding a rear (derailier) wheel as, to be frank, I used spokes
that were slightly smaller in diameter on the cassette side of the
wheel then probably wise, and had occasional spoke breakage. I finally
got some slightly larger diameter spokes and am lacing the cassette
side of the wheel.

Over probably a couple of years I had four spokes break, one at a
time, all were what Sheldon referred to as trailing spokes, the ones
that have the highest strain when pedaling, and all broke at the
middle of the bend at the head end.

While I was lacing the wheel with the new spokes I got to wondering
whether the side of the hub flange that spoke heads were on might have
had any effect on strength.

I have always laced 36 hole wheels over three for rear wheels and over
two for front wheels with the trailing spoke heads on the outside of
the hub flange and the leading spokes with the heads on the inside of
the flange, as I believe that Sheldon recommended.

But I also remember someone here with a rant about rear wheel lacing
who I think was recommending that on the cassette side that the heads
should all be toward the outside of the flange. I assumes to prevent
damaging spokes if the chain were to come off the largest cassette cog
and jam between the spokes and the cassette.

This is the only wheel I've had problems with and I deliberately
bought the bits and pieces with the idea of long life in mind -
cartridge wheel bearings and medium weight rim with eyelets, etc., and
as this is the only wheel that I've had problems with I'm fairly sure
that my wheel building technique is reasonably effective.

Any thoughts on spoke head orientation and the effect on spoke
strength.

I don't believe there is any meaningful difference in strength depending
on the spoke head orientation.

Sheldon recommends a specific head orientation based on the theory
that if the chain comes off on the wheel side that with the heads
outside (or maybe it was inside) there would be less chance of the
chain damaging the spoke.

My own experience is that if the chain does come off whichever spokes
are on the outside of the flange will get damaged :-(

Did you cold set the spokes at the bend to aim at the rim? If not the
elbow has the potential to flex with every rotation and work harden
until it breaks.

That might be the answer as the spokes broke at random intervals
measured in months and broke at the junction of the straight section
and the beginning of the curved section.
--
Cheers,

I'm rebuilding a rear (derailier) wheel as, to be frank, I used spokes
that were slightly smaller in diameter on the cassette side of the
wheel then probably wise, and had occasional spoke breakage. I finally
got some slightly larger diameter spokes and am lacing the cassette
side of the wheel.

Over probably a couple of years I had four spokes break, one at a
time, all were what Sheldon referred to as trailing spokes, the ones
that have the highest strain when pedaling, and all broke at the
middle of the bend at the head end.

While I was lacing the wheel with the new spokes I got to wondering
whether the side of the hub flange that spoke heads were on might have
had any effect on strength.

I have always laced 36 hole wheels over three for rear wheels and over
two for front wheels with the trailing spoke heads on the outside of
the hub flange and the leading spokes with the heads on the inside of
the flange, as I believe that Sheldon recommended.

But I also remember someone here with a rant about rear wheel lacing
who I think was recommending that on the cassette side that the heads
should all be toward the outside of the flange. I assumes to prevent
damaging spokes if the chain were to come off the largest cassette cog
and jam between the spokes and the cassette.

This is the only wheel I've had problems with and I deliberately
bought the bits and pieces with the idea of long life in mind -
cartridge wheel bearings and medium weight rim with eyelets, etc., and
as this is the only wheel that I've had problems with I'm fairly sure
that my wheel building technique is reasonably effective.

Any thoughts on spoke head orientation and the effect on spoke
strength.

--
Cheers,

John B.

FWIW I have always used the method described in Gerd Schraner's book on wheel building and I have no problems with wheels going out of true or spokes breaking. Schraner discusses your point and concludes that in his opinion it does not much matter whether the spokes at the hub are laced in a symetric or mirror image pattern or whether the driving spokes are head out or in. From his long experience of wheel building he has concluded that there should be a very marginal gain to have the driven spokes heads in on the cassette side and that is what he recommends. His logic being that it very slightly increases the angle to the rim and thereby slightly reduced tension. However it is clear he would not get into a flame war over it. His main contention is that it is the quality of the components and the build that determine how a wheel performs. On spoke elbow breakages he stresses the need to bed the spoke heads into the hub and to correctly tension and stress relieve the wheel.

Graham.

I tend to agree with you as I've built wheels in all sorts of style
and have seldom had any problems which was what was puzzling with this
particular wheel. It was straight and would go for months and then
pop, one spoke on the drive side would pop the head off and the wheel
would wobble. I'd take the wheel apart and check everything change the
spoke and re tension and it would go for months and then pop. The last
time it popped two spokes about 180 degrees from each other and I
decided to do something a bit more permanent and replaced all the
drive side spokes with a thicker spokes.

About thicker spokes: I do believe that butted spokes (thinner in the
middle) make stronger wheels.

When building new wheels before our biggest tour, IIRC I got butted
spokes with extra thickness at the end with the head. Sorry I don't now
remember the brand or gauge. It's been a long time.

I'm rebuilding a rear (derailier) wheel as, to be frank, I used spokes
that were slightly smaller in diameter on the cassette side of the
wheel then probably wise, and had occasional spoke breakage. I finally
got some slightly larger diameter spokes and am lacing the cassette
side of the wheel.

Over probably a couple of years I had four spokes break, one at a
time, all were what Sheldon referred to as trailing spokes, the ones
that have the highest strain when pedaling, and all broke at the
middle of the bend at the head end.

While I was lacing the wheel with the new spokes I got to wondering
whether the side of the hub flange that spoke heads were on might have
had any effect on strength.

I have always laced 36 hole wheels over three for rear wheels and over
two for front wheels with the trailing spoke heads on the outside of
the hub flange and the leading spokes with the heads on the inside of
the flange, as I believe that Sheldon recommended.

But I also remember someone here with a rant about rear wheel lacing
who I think was recommending that on the cassette side that the heads
should all be toward the outside of the flange. I assumes to prevent
damaging spokes if the chain were to come off the largest cassette cog
and jam between the spokes and the cassette.

This is the only wheel I've had problems with and I deliberately
bought the bits and pieces with the idea of long life in mind -
cartridge wheel bearings and medium weight rim with eyelets, etc., and
as this is the only wheel that I've had problems with I'm fairly sure
that my wheel building technique is reasonably effective.

Any thoughts on spoke head orientation and the effect on spoke
strength.

No, but the one time I had that I had over tensioned the wheel. Exact
symptoms you described. Backed off all the spokes, never had a breakage
in the subsequent 4(?) years.

Could be. I rarely use a spoke tension gauge and just tighten things
until they feel right so I might have over tensioned that wheel.

IMO, 14/15g spokes can take more tension than nipples or rims. If I over-tension a wheel, the nipples bind or the rim/spoke holes cracks. Rarely do I get a broken spoke. I've never broken a spoke while building, and I seriously wonder whether, with a tire inflated, tensions increase that much during load cycles. I haven't looked it up, but I doubt over-load failures are common with spokes. It's usually fatigue.

About thicker spokes: I do believe that butted spokes (thinner in the
middle) make stronger wheels.

In his book "The Bicycle Wheel" Jobst Brandt wrote: "However, the most
valuable contribution of swaging is that the peak stresses are absorbed
in the straight mid section that otherwise would be concentrated in the
threads and elbow, thereby substantially reducing fatigue failures."

A page later he continued, ""Although swaged spokes are more expensive
to manufacture and slightly more diffiuclt to true, they give more
durable wheels because they are more elastic than straight gauge spokes.
Their thin midsections stretch more, and they can be made just as tight
as straight gauge spokes. Under load, they resist loosening better than
straight spokes because they allow greater rim deformation before
becoming slack. Their resilience helps the rim distribute loads over
more spokes and reduces peak stress changes. Swaged spokes are also
lighter without giving up strength."

For me, it's been many years since I last had a spoke break. I suspect
that this is in part because of using fatter tires (26 x 2" or 27.5 x
2.25") that absorb more of the road shock.

I'm rebuilding a rear (derailier) wheel as, to be frank, I used spokes
that were slightly smaller in diameter on the cassette side of the
wheel then probably wise, and had occasional spoke breakage. I finally
got some slightly larger diameter spokes and am lacing the cassette
side of the wheel.

Over probably a couple of years I had four spokes break, one at a
time, all were what Sheldon referred to as trailing spokes, the ones
that have the highest strain when pedaling, and all broke at the
middle of the bend at the head end.

While I was lacing the wheel with the new spokes I got to wondering
whether the side of the hub flange that spoke heads were on might have
had any effect on strength.

I have always laced 36 hole wheels over three for rear wheels and over
two for front wheels with the trailing spoke heads on the outside of
the hub flange and the leading spokes with the heads on the inside of
the flange, as I believe that Sheldon recommended.

But I also remember someone here with a rant about rear wheel lacing
who I think was recommending that on the cassette side that the heads
should all be toward the outside of the flange. I assumes to prevent
damaging spokes if the chain were to come off the largest cassette cog
and jam between the spokes and the cassette.

This is the only wheel I've had problems with and I deliberately
bought the bits and pieces with the idea of long life in mind -
cartridge wheel bearings and medium weight rim with eyelets, etc., and
as this is the only wheel that I've had problems with I'm fairly sure
that my wheel building technique is reasonably effective.

Any thoughts on spoke head orientation and the effect on spoke
strength.

--
Cheers,

John B.

FWIW I have always used the method described in Gerd Schraner's book on wheel building and I have no problems with wheels going out of true or spokes breaking. Schraner discusses your point and concludes that in his opinion it does not much matter whether the spokes at the hub are laced in a symetric or mirror image pattern or whether the driving spokes are head out or in. From his long experience of wheel building he has concluded that there should be a very marginal gain to have the driven spokes heads in on the cassette side and that is what he recommends. His logic being that it very slightly increases the angle to the rim and thereby slightly reduced tension. However it is clear he would not get into a flame war over it. His main contention is that it is the quality of the components and the build that determine how a wheel performs. On spoke elbow breakages he stresses the need to bed the spoke heads into the hub and to correctly tension and stress relieve the wheel.

Graham.

I tend to agree with you as I've built wheels in all sorts of style
and have seldom had any problems which was what was puzzling with this
particular wheel. It was straight and would go for months and then
pop, one spoke on the drive side would pop the head off and the wheel
would wobble. I'd take the wheel apart and check everything change the
spoke and re tension and it would go for months and then pop. The last
time it popped two spokes about 180 degrees from each other and I
decided to do something a bit more permanent and replaced all the
drive side spokes with a thicker spokes.

About thicker spokes: I do believe that butted spokes (thinner in the
middle) make stronger wheels.

When building new wheels before our biggest tour, IIRC I got butted
spokes with extra thickness at the end with the head. Sorry I don't now
remember the brand or gauge. It's been a long time.

I could go measure measure, but I'm late heading for a big dinner.

Theoretically you are probably correct but I wonder whether this is
another of those Brandt situations where the difference is academic.

The difference in weight of a wheel built with butted spokes and non
butted spokes would be tiny and my guess that the difference in the
strength of the wheel would be would be, essentially meaningless. A
wheel that could support, oh say 1,000 lbs, and a stronger wheel that
would be, maybe 20% stronger is probably not meaningful when it comes
to bicycle wheels.
--
Cheers,

I'm rebuilding a rear (derailier) wheel as, to be frank, I used spokes
that were slightly smaller in diameter on the cassette side of the
wheel then probably wise, and had occasional spoke breakage. I finally
got some slightly larger diameter spokes and am lacing the cassette
side of the wheel.

Over probably a couple of years I had four spokes break, one at a
time, all were what Sheldon referred to as trailing spokes, the ones
that have the highest strain when pedaling, and all broke at the
middle of the bend at the head end.

While I was lacing the wheel with the new spokes I got to wondering
whether the side of the hub flange that spoke heads were on might have
had any effect on strength.

I have always laced 36 hole wheels over three for rear wheels and over
two for front wheels with the trailing spoke heads on the outside of
the hub flange and the leading spokes with the heads on the inside of
the flange, as I believe that Sheldon recommended.

But I also remember someone here with a rant about rear wheel lacing
who I think was recommending that on the cassette side that the heads
should all be toward the outside of the flange. I assumes to prevent
damaging spokes if the chain were to come off the largest cassette cog
and jam between the spokes and the cassette.

This is the only wheel I've had problems with and I deliberately
bought the bits and pieces with the idea of long life in mind -
cartridge wheel bearings and medium weight rim with eyelets, etc., and
as this is the only wheel that I've had problems with I'm fairly sure
that my wheel building technique is reasonably effective.

Any thoughts on spoke head orientation and the effect on spoke
strength.

--
Cheers,

John B.

FWIW I have always used the method described in Gerd Schraner's book on wheel building and I have no problems with wheels going out of true or spokes breaking. Schraner discusses your point and concludes that in his opinion it does not much matter whether the spokes at the hub are laced in a symetric or mirror image pattern or whether the driving spokes are head out or in. From his long experience of wheel building he has concluded that there should be a very marginal gain to have the driven spokes heads in on the cassette side and that is what he recommends. His logic being that it very slightly increases the angle to the rim and thereby slightly reduced tension. However it is clear he would not get into a flame war over it. His main contention is that it is the quality of the components and the build that determine how a wheel performs. On spoke elbow breakages he stresses the need to bed the spoke heads into the hub and to correctly tension and stress relieve the wheel.

Graham.

I tend to agree with you as I've built wheels in all sorts of style
and have seldom had any problems which was what was puzzling with this
particular wheel. It was straight and would go for months and then
pop, one spoke on the drive side would pop the head off and the wheel
would wobble. I'd take the wheel apart and check everything change the
spoke and re tension and it would go for months and then pop. The last
time it popped two spokes about 180 degrees from each other and I
decided to do something a bit more permanent and replaced all the
drive side spokes with a thicker spokes.

About thicker spokes: I do believe that butted spokes (thinner in the
middle) make stronger wheels.

When building new wheels before our biggest tour, IIRC I got butted
spokes with extra thickness at the end with the head. Sorry I don't now
remember the brand or gauge. It's been a long time.

I could go measure measure, but I'm late heading for a big dinner.

Theoretically you are probably correct but I wonder whether this is
another of those Brandt situations where the difference is academic.

The difference in weight of a wheel built with butted spokes and non
butted spokes would be tiny and my guess that the difference in the
strength of the wheel would be would be, essentially meaningless. A
wheel that could support, oh say 1,000 lbs, and a stronger wheel that
would be, maybe 20% stronger is probably not meaningful when it comes
to bicycle wheels.

To give a more general analogy: Bolts which are subject to rapid and
large variations in tension are sometimes made smaller diameter in their
center much like butted spokes. The math is a bit complicated, but this
can result in lower stress variation, therefore more fatigue resistance.
I believe this applies to bike spokes as well.

I don't think I can explain the math without a post that's a couple
pages long, though. And to be honest, I haven't tried to do the math in
detail for a spoked wheel. But I think the same principle applies to
both the bolts and the spokes.

I'm rebuilding a rear (derailier) wheel as, to be frank, I used spokes
that were slightly smaller in diameter on the cassette side of the
wheel then probably wise, and had occasional spoke breakage. I finally
got some slightly larger diameter spokes and am lacing the cassette
side of the wheel.

Over probably a couple of years I had four spokes break, one at a
time, all were what Sheldon referred to as trailing spokes, the ones
that have the highest strain when pedaling, and all broke at the
middle of the bend at the head end.

While I was lacing the wheel with the new spokes I got to wondering
whether the side of the hub flange that spoke heads were on might have
had any effect on strength.

I have always laced 36 hole wheels over three for rear wheels and over
two for front wheels with the trailing spoke heads on the outside of
the hub flange and the leading spokes with the heads on the inside of
the flange, as I believe that Sheldon recommended.

But I also remember someone here with a rant about rear wheel lacing
who I think was recommending that on the cassette side that the heads
should all be toward the outside of the flange. I assumes to prevent
damaging spokes if the chain were to come off the largest cassette cog
and jam between the spokes and the cassette.

This is the only wheel I've had problems with and I deliberately
bought the bits and pieces with the idea of long life in mind -
cartridge wheel bearings and medium weight rim with eyelets, etc., and
as this is the only wheel that I've had problems with I'm fairly sure
that my wheel building technique is reasonably effective.

Any thoughts on spoke head orientation and the effect on spoke
strength.

--
Cheers,

John B.

FWIW I have always used the method described in Gerd Schraner's book on wheel building and I have no problems with wheels going out of true or spokes breaking. Schraner discusses your point and concludes that in his opinion it does not much matter whether the spokes at the hub are laced in a symetric or mirror image pattern or whether the driving spokes are head out or in. From his long experience of wheel building he has concluded that there should be a very marginal gain to have the driven spokes heads in on the cassette side and that is what he recommends. His logic being that it very slightly increases the angle to the rim and thereby slightly reduced tension. However it is clear he would not get into a flame war over it. His main contention is that it is the quality of the components and the build that determine how a wheel performs. On spoke elbow breakages he stresses the need to bed the spoke heads into the hub and to correctly tension and stress relieve the wheel.

Graham.

I tend to agree with you as I've built wheels in all sorts of style
and have seldom had any problems which was what was puzzling with this
particular wheel. It was straight and would go for months and then
pop, one spoke on the drive side would pop the head off and the wheel
would wobble. I'd take the wheel apart and check everything change the
spoke and re tension and it would go for months and then pop. The last
time it popped two spokes about 180 degrees from each other and I
decided to do something a bit more permanent and replaced all the
drive side spokes with a thicker spokes.

About thicker spokes: I do believe that butted spokes (thinner in the
middle) make stronger wheels.

When building new wheels before our biggest tour, IIRC I got butted
spokes with extra thickness at the end with the head. Sorry I don't now
remember the brand or gauge. It's been a long time.

I could go measure measure, but I'm late heading for a big dinner.

Theoretically you are probably correct but I wonder whether this is
another of those Brandt situations where the difference is academic.

The difference in weight of a wheel built with butted spokes and non
butted spokes would be tiny and my guess that the difference in the
strength of the wheel would be would be, essentially meaningless. A
wheel that could support, oh say 1,000 lbs, and a stronger wheel that
would be, maybe 20% stronger is probably not meaningful when it comes
to bicycle wheels.

To give a more general analogy: Bolts which are subject to rapid and
large variations in tension are sometimes made smaller diameter in their
center much like butted spokes. The math is a bit complicated, but this
can result in lower stress variation, therefore more fatigue resistance.
I believe this applies to bike spokes as well.

I don't think I can explain the math without a post that's a couple
pages long, though. And to be honest, I haven't tried to do the math in
detail for a spoked wheel. But I think the same principle applies to
both the bolts and the spokes.

Bolts, spokes, tie-rods, etc, :-)

Most reciprocating radial aircraft engines were built with several
aluminum sections bolted together and yes, the through bolts were all
"waisted" ( is that the terminology for a bolt with a reduced diameter
in the center? ) They were torque at ambient temperature and one
assumes retained some minimum pressure when everything had warmed up.

I suspect that the calculations were a bit complex what with expansion
of various materials with temperature change, load changes with
internal parts whizzing around inside, the entire induction section
subjected to water injection at take off power, etc.

But every damned one of them leaked oil :-)

Out of curiosity I did a search for "MG TC wheel spoke" and yes, they
made butted spokes for them.

But like spoke tieing I wonder whether they are really a necessity :-)
--
Cheers,